| The preparing of a novel nano-SiO_x antimicrobial material and its mechanism were studied in this paper. First, nano-SiO_x was treated by activation substances, then reacted with high-molecular-weight polyethylenimine(PEI) in organic solvent, so PEI was grafted covalently on the surface of nano-SiO_x, finally, modified it by the halide such as bromohexane and iodomethane, then high-molecular-weight quaternary ammonium salts was prepared. The bactericidal activity of the antimicrobial nano-SiO_x was evaluated, the results showed, Gram-positive bacteria, Gram-negative bacteria, yeast and mold were killed dramatically, then the bactericidal capability was analysised at different period during one year. At last, we found the antimicrobial capability of nano-SiO_x had little reduction, it demonstrated that the nano-SiO_x had a prolonged action and bactericidal stability.The sterilization mechanism of nano-SiO_x was studied. Dehydrogenase created during respiratory metabolism of Gram-positive, Gram-negative bacteria and yeast were inhibited completely when then concentration of nano-SiO_x reached 1mg/ml, metabolism process was terminated. The concentration determine of DNA, RNA andβ-galactosidase indicated that inner substance of bacteria cells leaked out into solution, this also demonstrated that nano-SiO_x had degtadation against the cell wall and membrane. Fluorescent staining of bacteria and yeast was detected, the cells reacted by nano-SiO_x were mostly stained, which indicated that the cell membrane was destroyed, for propidium iodide can only enter the incomplete cells, stained the cellular nucleus. Shape variety of bacteria and antimicrobial process could be observed through TEM. The action was composed of two steps, first adsorption, then cell-lysis. There was strongly electrostatic interaction between nano-SiO_x and cells. After adsorption, cell membrane destroyed, then intracellular components leaked out, finally decomposed. |
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